Method of sterile packing of sterile goods



Jan. 5, 1965 w. LOLIGER ETAL 3,153,971

' METHOD OF STERILE PACKING OF STERILE GOODS Filed Dec. 8, 1961 K a .lmerrzars MILL! LOL IGE/E.

ML. r52 PEGEZ.

United States Patent 3,163,971 METHQD 0F STERLLE PACKlNG 9F STERKLE GO0DWilli Liiiiger, Konolfingen, and Walter Regez, hiuri, near Bern,Switzerland, assignors to Aipura AG, Bern, witzerland, a corporation ofSwitzerland Filed Dec. 3, 1961, Ser. No. 158,170

Ciairns priority, application Switzerland Dec. 16, 1960 8 Clair-i s.((11. S328) The invention relates to a method of sterile packing ofsterile goods wherein a flexible packing material of paper or plastic orthe like is sterilized by heating of that side of the material whichsubsequently contacts the goods to be packaged. The invention relatesmore particularly to a method wherein a tube of flexible material isformed continuously in a packing and filling machine, Whereafter thetube is partly filled with the substance to be packed and formed intoclosed filled receptacles by compression transversely of its length, theinside of the formed tube being heated at a location between theintroduced substance and the opening of the tube at the location whereformation of the tube begins.

Temperatures of 200 C. or more are usually necessary to destroy harmfulgerms. It has been found that when the method described supra is used inpractice it is sufiicient, when packing milk, to heat the inside of thetube to a temperture of about 300 C. to destroy heatresistant germs.However, the required temperature depends upon the duration of theheating time. It is known that the required temperature is greater ifthe heating time is shorter, and conversely. Of course, it is desired touse high temperatures in order to reduce the heating time and tocorrespondingly increase the speed of packing and filling if formationand filling of the receptacles is continuous.

Heating is limited by the properties of the packing material used and ifthe limits are exceeded, the packing material may be damaged. Thisapplies more particularly to paperlike packing material which has a thinlayer of plastic, preferably polyethylene, on the side which engageswith the packed goods. As a rule, the thickness of such a layer is onlya few hundredths of a millimeter. The layer serves to provide hermeticsealing of the paperlike packing mate-rial and sealing againstpenetration of germs and, where the receptacles are filled with liquids,against moisture soaking through to the outside of the receptacle. Paperand plastics are poor heat conductors. Therefore, if a short heatingtime and correspondingly high heating temperature are used, thetemperature of the surface of the heated side of the material may risevery rapidly because of non-dissipation of the heat supplied, thetemperature possibly rising to beyond the temperature required forsterilization, particularly if the heating device is a radiant heater.

This abrupt temperature rise may damage the heated side of the material.As a rule, polyethylene is fusible at temperatures above 100 C., whilepaper becomes more brittle if heated abruptly. Consequently, and alsobecause of the stresses produced over the thickness of the material,minute cracks may open up in the plastic layer or on the paper surfaceand destroy hermetic sealing, involving the risk of reinfection byexternal germs.

Plastic layers oxidize in the presence of oxygen and ice particularly atelevated temperatures. Such oxidation impairs the properties of theplastic; it becomes more brittle and its weldability decreases so thatthe tightness of the welds made when closing the receptacles may beunsatisfactory.

It is an object of the invention to provide a method for sterile packingof sterile goods whereby the aforedescribed disadvantages areconsiderably reduced. In the method according to the invention at leastthat side of the material which must be heated for sterilization ismoistened at the latest at the time when said side passes through theheating zone. The effect of this step is that, when the side of thematerial is heated, the temperature rise in the surface part of thematerial is initially reduced by the heating and evaporation of themoisture on or in the mate-rial, so that harmful stresses areconsiderably reduced and the risk of cracking the plastic is reduced. Afairly dense vapor cushion is produced which keeps atmospheric oxygenaway from the plastic and thus re duces oxidation thereof. Further, thesterilizing eifect of the heating is increased, for germs such asbacteria and spores are less resistant in moist heat than in dry heat.

Preferably a wetting agent it is added to the moistening liquid toensure a very uniform liquid film on the side of the packing materialwhich must be protected. It is advisable to remove surplus liquid whichdoes not adhere to the packing material, before the heating zone isentered because, otherwise, if the material passes ver tically throughthe heating zone, there is a chance that drops of moistening liquid runoif or drop down and come in contact again with the material below theheat ing zone, which is either detrimental to the goods to be packed ormay cause reinfection because of germs present in the moistening liquid.

It may be advisable to moisten also that side of the packing materialwhich will subsequently form the outside of the finished packages, moreparticularly the moisture-absorbent paper side of paper webs having oneside coated with a synethetic substance. A chemically active sterilizingagent may be added to the moistening liquid for improving thesterilization eifect. This may make it possible to reduce the maximumheating temperature.

The novel features which are considered characteristic of the inventionare set forth with particularity in the appended claims. The inventionitself, however, and additional objects and advantages thereof will bestbe understood from the following description of embodiments thereof whenread in connection with the accompanying drawing wherein:

FIG. 1 is a vertical sectional view of a filling and packing machine inwhich a tube is formed from a continuous paper strip, partly filled andformed into closed filled receptacles by compression transversely to thelongitudinal extension of the tube, the web passing through a moisteningdevice before the tube is formed and heated.

FIG. 2 is a sectional view through a moistening device used in themachine shown in FIG. 1.

FIG. 3 illustrates a portion of a tube having a part broken off to showa heating device disposed in the tube, and a modified moistening deviceabove the heating device.

The filling and packing machine illustrated, by Way of*AlkyI-aryl-sulfonate.

example, in the drawing comprises a casing 1 supporting a column 2. Aweb of paper coated on one side with a plastic, such as polyethylene, isdrawn continuously off a reel, not shown, and supplied to the packingmachine and is guided in a ring 3 so as to form a tube 5', the coatedside of the web forming the inside wall of the tube. The side edges ofthe web 5 overlap one another. A heating pad 7 secured to a support 6bears against the overlapped parts of the web 5 for connecting the partsby welding. A roller is provided inside of the formed tube adjacent tothe overlapped parts and opposite the heating pad 7 for efiectingcontact between the heating pad and the web. The pad 7 is electricallyheated,

I Electrically heated pressing jaws 1d and 11 secured to endless chains12 and 13, respectively, and traveling therewith when the apparatus isin operation are provided inside the casing 1. The chain 12 runs overguide wheels 14, 15, while the chain 13 runs over guide wheels 16, 17,the wheels 14 and 17 or the Wheels 1'5 and 16 being adapted to berotated, by drive means which are not shown, to move the chains in thedirection indicated by arrows 18 and 19. Other pair of pressing jaws,not shown, are operative perpendicularly to the plane of the drawing sothat the tube 5, which continuously moves in downward direction, isalternately compressed in two directions perpendicularly to one another.The move ment of whichever pressing jaws engage the tube 5 imparts adownward drive on the tube while closed receptacles 24) are formed. Thegoods to be packed, for instance sterilized milk, are supplied to theapparatus through filling pipe 21 which is borne by a sleeve 2supporting at its bottom end the roller 9. The sleeve 24 is secured toan arm 4 extending from the column 2. The supply of milk is socontrolled by means, not shown, that a constant liquid level 22 ismaintained within the tube 5'.

' A radiant heating device 25, for example, of the type which will bedescribed hereinafter with reference to FIG. 3, is disposed in theformed tube 5' above the introduced goods and surrounds the filling pipe21.

Before entering the packing and filing machine the web 5 passes througha moistening device denoted in its entirety by the reference numeral 26.The device 26 is shown in section in FIG. 2 and comprises a tank 27 formoistening liquid and two deflecting rollers 28, 29. The roller 28 dipsbelow the level 3i? of the moistening liquid, for. instance water, towhich an appropriate wetting agent can be added. Any surplus liquidwhich is carried along by the moving web 5 and which would drop down ifthe web moves vertically, returns on the upwardly incline'd part of theWeb 5 between the two rollers.

When the aforedescribed apparatus is in operation, the continuouslysupplied web is moistened on both sides, then formed into a tube andheated by the heating device 25 on the inside of the tube whereby theliquid which adheres as a film to the inside of the tube is evaporatedand the temperature rise of the tube inner wall is reduced. The vaporforms a buffer rising along the inside of the tube and being partlysuperheated. After passing through the heating zone the inside of thetube is completely dry until it contacts the milk filled into the tube.

FIG. 3 illustrates an embodiment wherein moist-ening is performed insidethe tube formed in a filling and packing machine of the kind shown inFIG. 1. An annular duct 31 is placed in the interior of the tube 5around the filling pipe 21 and is secured thereto in a suitable manner.Moistening liquid is suppliedthrough a connecting pipe 32 to theinterior of the duct 31, the pipe 32 extending out of the top of thetube 5'. Nozzlelike apertures 33 are provided at the periphery of the Iduct 31 through which pressurized moistening liquid is sprayed in veryfine jets onto the inner wall of the tube 5'. Larger drops areintercepted by an interceptor ring 34 whose o ter rim touches the insideof the tube and which is made of a heat-resistant resilient substance.Below the moistcning device is a heating device 35 which comprises anannular chamber 36 containing heating coils 37. The heating device 35 iscovered at the top by a heat-insulating layer 38 made of mica or thelike.

An appropriate chemical sterilizing agent may be ad mixed to themoistening liquid. A solution of hydrogen eroxide has been foundsuitable.

The invention is not limited to the embodiments illustrated and can beused in machines wherein packing receptacles are formed in a differentWay from a packing material which must be sterilized at least on theside subsequently forming the inside of the finished receptacles.Heating may be eiiected by means of a gaseous or vaporlike heat carrier.Moistening may be performed within the heating zone instead of upstreamof that zone.

We claim:

1. In a method of sterile packing of sterile goods wherein a verticaltube is continuously formed from longitudinally moving strip like,flexible packing material, the tube is closed by compression transverseto the longitudinal axis of the tube, and the goods are filled into thetube, whereupon the tube is closed again by compression transverse tothe longitudinal axis of the tube, the steps of:

heating the interior of the formed tube at a location above the goodsfor sterilizing the interior of the tube, moistening, before the packingmaterial reaches said heating location, at least the side of the packingmaterial whi h forms the inside of the tube,

retaining the moisture on the packing material until the packingmaterial reaches said heating location, and

evaporating the moisture by part of the heat which heats the interior ofthe formed tube to reduce the initial temperature rise in the heatedpacking material and to produce a vapor cushion adjacent said heatinglocation.

2. In a method of sterile packing of sterile goocs wherein a verticaltube is continuously formed from longitudinally moving striplike,flexible packing material, the tube is closed by compression transverseto the longitudinal axis of the tube, and the goods are filled into thetube, whereupon the tube is closed again by compression transverse tothe longitudinal axis of the tube, the steps of:

heating the interior of the formed tube at a location above the goodsfor sterilizing the interior of the tube,

applying a moistening liquid, before the packing material reaches saidheating location, at least to the side of the packing material whichforms the inside of the tube,

retaining the moistening liquid on the packing material until thepacking material reaches said heating location, and

evaporating the moistening liquid by part of the heat which heats theinterior of the formed tube to reduce the initial temperature rise inthe heated packing material and to produce a vapor cushion adjacent saidheating location.

3. In a method as defined in claim 2 and wherein said moistening liquidcontains a wetting agent.

4. In a method as defined in claim 2, the step of removing surplusmoistening liquid prior to sterilization of the inside of the tube byheating.

5. In a method as defined in claim 2 and wherein said moistening liquidcontains a sterilizing agent.

6. In the method defined in claim 2 wherein said moistening liquid iswater.

7. in the method defined in claim 2 wherein said moistening liquid is asolution of hydrogen peroxide.

8. In a method of sterile packing of sterile goods where- D in avertical tube is continuously formed from longitudinally movingstriplilie, flexible packing material, the tube is closed by compressiontransverse to the longitudinal axis of the tube, and the goods arefilled into the tube, whereupon the tube is closed again by compressiontransverse to the longitudinal axis of the tube, the steps of:moistening the inside of the formed tube at a location spaced from andabove the goods in the tube,

heating the interior of the formed tube at a location above the goodsand below the location Where the 10 inside of the tube is moistened, and

8 evaporating the moisture by part of the heat Which heats the interiorof the formed tube to reduce the initial temperature rise in the heatedpacking material and to produce a vapor cushion adjacent said heatinglocation.

References Cited in the file of this patent UNITED STATES PATENTS2,918,770 Stocker Dec. 29, 1959 2,928,219 Gubler Mar. 15,1960 3 ,663,211Graves Nov. 13, 1962

1. IN A METHOD OF STERILE PACKING OF STERILE GOODS WHEREIN A VERTICALTUBE IS CONTINUOUSLY FORMED FROM LONGITUDINALLY MOVING STRIPE LIKE,FLEXIBLE PACKING MATERIAL, THE TUBE IS CLOSED BY COMPRESSION TRANSVERSETO THE LONGITUDINAL AXIS OF THE TUBE, AND THE GOODS ARE FILLED INTO THETUBE, WHEREUPON THE TUBE IS CLOSED AGAIN BY COMPRESSION TRANSVERSE TOTHE LONGITUDINAL AXIS OF THE TUBE, THE STEPS OF: HEATING THE INTERIOR OFTHE FORMED TUBE AT A LOCATION ABOVE THE GOODS FOR STERILIZING THEINTERIOR OF THE TUBE, MOISTENING, BEFORE THE PACKING MATERIAL REACHESSAID HEATING LOCATION, AT LEAST THE SIDE OF THE PACKING MATERIAL WHICHFORMS THE INSIDE OF THE TUBE, RETAINING THE MOISTURE ON THE PACKINGMATERIAL UNTIL THE PACKING MATERIAL REACHES SAID HEATING LOCATION, ANDEVAPORATING THE MOISTURE BY PART OF THE HEAT WHICH HEATS THE INTERIOR OFTHE FORMED TUBE TO REDUCE THE INITIAL TEMPERATURE RISE IN THE HEATEDPACKING MATERIAL AND TO PRODUCE A VAPOR CUSHION ADJACENT SAID HEATINGLOCATION.